1. Field of the Invention
The invention is directed to a heat-sensitive recording material having a substrate which carries on its first side at least one heat-sensitive recording layer and on its second side a backcoat containing calcium carbonate. The heat-sensitive recording layer has at least one dye precursor and at least one color acceptor which react with one another in a color-forming manner under the action of heat.
2. Detailed Description of Prior Art
The stated object in WO99/14056 A1 is a backcoat having a good barrier effect with respect to substances used in offset printing and flexographic printing, particularly organic solvents, and with respect to plasticizers, oils and fats, is motivated by the desire to print on the back side of a heat-sensitive recording material in offset printing and flexographic printing. In order to meet the object stated therein, the backcoat of the known recording material has a mixture containing starch, an acrylate copolymer which does not include any styrene or vinyl acetate components and which has a film-forming temperature of less than 5° C., preferably less than 2° C., and an alkaline catalyst such as, e.g., calcium carbonate.
Accordingly, it is known from the above-cited publication to use the back side of heat-sensitive recording materials as a substrate for offset printing. Other recording materials known from the prior art have also proven successful as concerns the barrier effect against the chemicals employed in this connection. However, when aiming for high-quality pigment-containing backcoats, for example, for full-surface multicolor printing, severe difficulties were sometimes encountered in the past during the actual printing process with its requirements respecting the surface to be printed upon, since trouble-free and, therefore, efficient printing is hampered by deposits on the blanket. But the principle focus of criticism in previous proposals was the disappointing print image of pictures printed on the back side and the largely insufficient gloss of the back side. Accordingly, if multicolor printed images are to be applied to the back side of heat-sensitive recording materials with a quality approaching that of an art print, as is called for in the case of many commercial tickets, novel, previously unavailable solutions are needed.